/*
 * Copyright 2020-2030 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.extraty.question2;

/**
 * @author Created by Neil Wang
 * @version 1.0.0
 * @date 2021/8/30 5:31 下午
 */
public class Solution1 {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        return createListNode(l1.next, l2.next, l1.val + l2.val);
    }

    private ListNode addTwoNumbers(ListNode l1, ListNode l2, int decimal) {
        if (l1 == null && l2 == null && decimal == 0) return null;
        if (l1 == null && l2 == null) return new ListNode(decimal);
        if (l1 == null) return createListNode(null, l2.next, l2.val + decimal);
        if (l2 == null) return createListNode(l1.next, null, l1.val + decimal);
        return createListNode(l1.next, l2.next, l1.val + l2.val + decimal);
    }

    private int getNum(int num) {
        return num % 10;
    }

    private int getDecimal(int num) {
        return num / 10;
    }

    private ListNode createListNode(ListNode l1, ListNode l2, int number) {
        return new ListNode(getNum(number), addTwoNumbers(l1, l2, getDecimal(number)));
    }

}
